Metallized fabric



May 29, 1956 A. F. SCHRAMM, JR

METALLIZED FABRIC Filed Oct. 1. 1955 INVENTOR. flujasi 17' Jclzramm, /11

United States Patent METALLIZED FABRIC August F. Schramm, Jr., WhitePlains, N. Y.

Application October 1, 1953, Serial No. 383,593

2 Claims. (Cl. 117-31) This invention relates to metallized sheetmaterial and the method of making it. The invention relates, moreparticularly to a sheet of textile fabric or the like having on onesurface at least thin flakes of metal adhered to the sheet.

There have been numerous efforts to increase the heat insulating effectof fabric by applying a layer of minute particles of aluminum foil overthe fabric. An article of this type is that described in U. S. Patents2,630,573 and 2,630,620. In the process and product of these patents,permeability of air breathing properties is dependent uponinaccessibility of certain parts of the fabric structure to the appliedmetallizing composition and film rupture after application of thecomposition, or is introduced by baking and consequent shrinkage of thepreviously applied plastic and aluminum composition. Also the flakes aresuspended in a solution of plastic in which they are sprayed upon thefabric, so that the flakes in the finished product are covered on facesand edges by plastic material.

In my improved metallized fabric spaces between the metal flakes are infree communication with the meshes in the fabric or other openings inthe treated sheet material. Smoke may be blown freely through thetreated product; easy permeability to air is thus demonstrated. Myprocess makes unnecessary breaking, distortion, or baking to causeshrinkage of previously applied material. My process avoids the use oforganic solvents which frequently involve fire hazard as well asexpense.

Briefly stated, my invention comprises the process of and the productresulting from applying, to a surface of a permeable sheet, fineparticles of normally solid binder material dispersed in a liquidnon-solvent for the binder material, then applying to the same surfacesmall flakes of metal in uncovered form, that is, not suspended in aplastic or like solution, volatilizing the liquid non-solvent from thedispersion, pressing the flakes of metal against the binder while thebinder is in softened condition, and then hardening the binder.

This application is a continuation in part of my copending applicationfor U. S. patent Serial No. 372,406 filed August 4, 1953. The inventionutilizes parts of the technique of equipment described in my Patent2,603,575 issued on July 15, 1952.

The invention will be illustrated by description in connection with theattached drawings to which reference is made.

Fig. 1 is a diagrammatic side view of suitable equipment for use inpractising the process of the invention.

Fig. 2 is a plan view of the metal-coating roller.

Fig. 3 is a magnified perspective view of the finished, metallizedfabric partly broken away for clearness of illustration with the binderparticles, metal flakes, and

This is mounted on conventional support 4, drawn over guide roller 6,and then over reverse coating roller 8 operated by the directly drivenroller 10 which, at its lower portion, dips into the tank 12 of aqueousemulsion 14 of binder material. The film of binder emulsion supplied tothe fabric by the roller 8 is shown in exaggerated thickness at 16.

Driven roller 18, for supplying metal powder to the surface of thefabric carrying the previously applied dispersion of the binder, dipsinto metal powder 19 in container 20. Doctor blade 22, in a usual kindof mounting, supplies a straight edge adjacent to the surface of theroller 18 after issuance, in its rotation, from the tank of metalpowder, so as to control the thickness of layer of the powder whichpasses under the doctor blade to the fabric. Control and positiveness offeed is also effected in part by the diagonal grooves or engravings 24on the metal supply roller 18.

Roller 26 rests upon the sheet material 2 at a position just above theroller 18, so that there is slight but appreciable pressure of the metalparticles at this point against the binder dispersion on the cloth.

A thin layer 28 of the metal flakes remains on the cloth issuing fromthe pass between the rollers 18 and 26.

The cloth with binder and metal flakes then passes against a tappingdevice such as the member 30 of hexagonal cross section driven in rapidrotation. The edges of the hexagonal member, striking back of the clothat closely spaced intervals, causes falling away of flakes of the metalnot adhered to the sheet material, that is, not in direct contact withparticles of the binder material on the surface of the sheet.

Receiver 31 for the metal flakes so removed terminates close to thetreated side of the sheet material and is suitably under slight vacuum,so that there is a gentle movement of air through the sheet material.While not necessary to permeability of my product, this slow movement ofair causes additional removal of insecurely lodged metal. To avoidscraping action, small guide rollers 32 are provided at the positions ofcontact of the vacuum line with the treated surface of the fabric. Theremaining layer of metal flakes extends over all parts of the face ofthe cloth, that is, over the positions of intercrossing of the strandsthereof and also over the meshes therebetween.

The sheet with adhered binder and metal flakes is passed through a mistspray chamber 33 with spray nozzle 34. Here there is applied a lightmist of binder material, suitably the same in composition as emulsion14, in limited amount covering, after drying, less than all of thesurface of thesheet, so as to leave pore spaces but uniting itself tothe binder initially applied.

The sheet is then plied, in one embodiment of the invention, withpermeable sheet 35 of the same kind as sheet 2 or different. Thecomposite or laminate so made is pressed between rollers 36 which forcethe sheet 35' lightly against the freshly sprayed binder. Sheet 35carries spaced particles 39 of previously applied binder material.

The treated sheet material is then drawn through the warming chamber 37with heating elements 38 and vent to the hood 40, for exhausting vaporof the non-solvent which is evaporated from the binder dispersion in thewarming chamber.

The dried composite then passes in warm condition between the smoothingrollers 42 and 44. These press the metal flakes flatwise with respect tothe sheet material and firmly against the plastic binder material thathas been softened in the warming chamber 37.

The product then passes through the cooling chamber 46 provided withinlet 48 for cold air and outlet 50. The cooled product then passes overguide roller 52 to usual winding up mechanism 54, care being taken atall times to avoid stretching the cloth to the point of rupture of thebinder and aluminum structure thereon.

Driving mechanisms and other accessories to the machine that are notillustrated are conventional. Also materials used in construction of thevarious parts of the machine are those conventionally used for likeparts in other machines except as noted herein. Suitably, the roller issteel with a cloth cover over its cylindrical surface, the roller 8rubber faced, and the hexagonal roller 30 of steel.

The process will be largely evident from the description of theapparatus that has been given.

Plastic binder material is supplied to one surface at least of the sheetmaterial, in limited proportion less than that required to saturate thesheet. In fact the amount is just enough to moisten the face of thesheet. Then a thin layer of the metal flakes is applied over thedispersion on the sheet. Those of the metal flakes so applied that arenot in direct contact with the binder, as shown by non-adherence areremoved as by a tapping operation on the back of the sheet while theparticles are on the lower side of the sheet. Those not adhered inposition are removed by the tapping operation, supplemented in oneembodiment of the invention, by those removed also by a slow stream ofair drawn through the sheet in the direction of back to face.

The sheet with the binder and adhered particles are subjected to theelevated temperature of volatilization of the non-solvent liquid medium,in which the binder particles are originally dispersed, and of softeningof the normally solid binder material. Before the particles of binderhave become solid, the flakes of metal are pressed against the binder,generally flatwise with respect to the sheet. The rollers 42 and 44,being cold, set the binder. Then the binder is hardened, as by beingcooled from an elevated temperature of softening of it to roomtemperature.

As to materials, my process is intended for use on textile fabrics ofcotton, wool, rayon, and synthetics or mixtures theerof. In such woven,knitted or braided sheet material, the spaces between the metal flakescommunicate directly with the meshes between the strands of the fabricas well as at positions where the threads cross each other. Other sheetmaterial may be used, however, including air permeable felted fibrousmaterial, of which paper is an example, and fabrics pretreated for waterrepellency.

The metal particles are suitably in the formiof flakes of metal foil,that is, flakes of the thinness of metalfoil. Examples are aluminum andbronze powders of the fineness of such powders designed for use aspigment in lacquers. Stainless steel powder is another example. For bestreflection of radiant energy, aluminum flakes are used. Because of theanchorage secured by my pressing operation, that orients the particlespredominantly in direction generally parallel to the surface of thesheet material being metallized, excessive fineness of the particles isnot required. Sizes of 100 mesh and finer are satisfactory.

The binder material must be non-volatile, water insoluble, waterdispersible, and normally a solid, this term including a plastic solid.Examples of binder materials that meet these requirements and that areused to advantage are thermoplastic materials including polyvinylchloride and copolymers with vinylidene chloride or vinyl acetate,polystyrene, the polymethacrylates such as polymethyl methacrylate,polyvinylbutyral, and cellulose acetate, all as used being in the formof any commercial emulsion of the plastic.

These particles as used in the emulsion are in part at least colloidalor microscopic in size and constitute the dispersed phase in a mediumconsisting largely or wholly of water or other liquid non-solvent forthe hinder, the liquid containing any stabilizer or emulsifier that iscommercially used to increase the stability or dispersibility of thebinder material in the non-solvent. A suitable size is l0.05 micron forparticles constituting at least half of the total weight of the bindermaterial.

The particles of binder material contain the proportion, if any, ofplasticizer required for non-brittleness of the binder material afterdrying. The plasticizer selected is one that is conventional for theplastic binder used. Examples of the plasticizers are dioctyl phthalateor adipate, dibutyl sebacate, tributoxyethyl phosphate, and butyl cresylphosphate.

The temperature of softening of the binder material applied in theemulsion is chosen in accordance with the properties desired in thefinished, plastic treated fabric. For treating goods that are towithstand boiling water temperature, I use plastic material that doesnot soften to the tacky condition at such temperature. For goods thatwill never be subjected to such an elevated temperature, the plasticchosen may have a lower softening point. For a given kind of plasticselected, I control the softening point by the proportion ofplasticizer, as within the range 20%-50% of plasticizer on the weight ofthe unplasticized plastic. The greater the proportion of plasticizer,the lower the softening point.

All of the materials used in my process and article are chemicallyinert, that is, non-destructive of each other.

As to other proportions, I use a large proportion of water in theemulsion of the binder material, so that v evaporation of water from theapplied material leaves than water.

spaces between adjacent particles of the binder. While this proportionof water may vary with the different natures of the selected bindermaterial, I find a proportion of water within the range 30-70 parts ofwater to 100 of the total emulsion to be satisfactory. The proportion ofwater within the stated range is decreased as the total amount ofapplied plastic emulsion is made very low per square yard. The portionof water may be increased, on the other hand, as thicker layers orlarger proportions of the emulsion are applied over the fabric.

The emulsion of binder material should be used in concentration and inamount applied to leave about 0.3-1 oz. of binder, dry weight, persquare yard of fabric treated. This gives proper adherence of the metalflakes later applied and also leaves the desired spaces through thebinder after the water is removed. The amount of the emulsion appliedwill in general be less, for a given permeability of the finishedtreated fabric, when the cloth treated is one that is closely woven, andthe amount will be larger for relatively very open mesh fabrics. Theamount of emulsion, being less than the saturation proportion, is lessthan that which, if applied, would make impossible, after drying, theblowing of cigarette smoke through the fabric with the mouth, theblowing through of smoke being evidence of preservation of permeabilityto air. The emulsion penetrates the surface only of the fabric.Subsequent drying leaves the originally emulsified plastic particlesembedded or anchored in the surface of the fabric.

There is no need to use any non-solvent liquid other Besides its lowcost, water is non-hazardous in use and entirely satisfactory in myprocess.

The invention will be further illustrated by description .in connectionwith the following specific examples of the practice of it.

Example 1 A woven cotton fabric (canvas) is given a light coating byroller 8 of a polyvinyl chloride emulsion known as Geon 576 latex. Thiscontains 35 parts of dioctyl phthalate plasticizer for 100 of polyvinylchloride, the

emulsion having been reduced in concentration before to the extent of atleast through 200 mesh screen.

7 The mist spray shown in the drawing as applied by nozzle 36 and alsothe additional sheet material 35 are omitted in this example. Thisleaves the applied metal flakes uncovered over their surface away fromthe canvas.

The canvas, with the applied emulsion of the thermoplastic bindingmaterial and the subsequently applied aluminum flakes, is heated in thechamber 37 to a temperature of 8090 C. by radiant electric resistanceheaters 38, cooled by passage through the chamber 46 supplied through 48with a draft of cold air, and then wound at 54. Rollers 42 and 44 andthe additional sheet 35 are omitted in this example. The product isfinished otherwise as described above.

Example 2 The procedure of Example 1 is followed except that a lightmist of the emulsion of binder material 14 is applied in the chamber 33.The amount of this mist is such that it does not give a continuouscoating on the layer of aluminum particles after the subsequent dryingoperation, but leaves plastic with spaces therethrough for air breathingproperties, these spaces communicating with the openings in the meshesof the canvas. This binder applied in the form of the mist leaves, ondrying, spaced minute spots of plastic that adhere in part to the metalflakes and in part to the binder applied initially to the canvas.

Example 3 The procedure of Examples 1 or 2 above is followed with thesubstitution of any of the other binder materials disclosed herein, anyof the other kinds of metal flakes, or paper for the polyvinyl chlorideplastic, aluminum flakes, and canvas, respectively.

Example 4 The procedure of Example 2 is followed with the exception thatan additional layer 35 of sheet material is applied against the freshlysprayed mist of binder material. This additional sheet material isprovided in advance with spaced particles of thermoplastic material asdescribed in my said copending application. These particles are insidein the laminate, soluble in the binder first applied, and, in thefinished product, adhere the additional sheet over the metallizedsurface of the first sheet. The laminate is finished by passage betweenthe compositing rollers 36, drier 37, between the pressing rollers 42,through the cooler 46, and to the winding 54. Fig. 4 shows a view of thethus made, laminated product.

Example 5 This example represents a modification of the inventionillustrated in Examples 1-4.

In this example, the aluminum flakes 19, supplied by roller 18 to thefabric 2, are premixed with solid particles of a thermoplastic bindertherefor. The thermoplastic binder is suitably of the same compositionas that shown at 39. It is in the form of fine but macroscopic particlesof the fineness, for instance, of coarse wheat flour or fine corn meal.

The proportion of the metal flakes to the binder material mixedtherewith in the vessel 20 may vary considerably. Suitable proportionsare 50-95 parts by weight of the binder for 100 parts of total weight ofthe mixed binder and metal flakes. In this particular example, I use 90parts of the thermoplastic binder of the same kind as that shown at 39for parts by Weight of flake aluminum.

The beater 30, tapping on the back of the cloth with the appliedemulsion 16 and the subsequently applied mixture of aluminum flakes andmacroscopic binder particles, dislodges and removes from the sheet thoseof the aluminum flakes and of the said macroscopic particles that arenot in direct contact with the emulsion-wetted surface of the sheet.

In this example, the spray 39 of additional thermoplastic binder andalso the plying with the additional sheet material 35 are omitted, thesheet 2 with the applied emulsion and premixed aluminum flakes andmacroscopic particles of binder being passed directly between the dryingand heating units 38 and the compression rollers 42 to the cooler 46 andto the winding mechanism.

Example 6 The procedure of Example 5 is followed except that the spray39 of additional binder material and the laminating sheet 35 are appliedand the product finished as previously described in connection with thelaminating operation in Example 4.

Example 7 The procedure of Example 5 is followed with the followingchanges.

The premixed aluminum flakes and macroscopic solid particles ofthermoplastic binder are applied from above as a layer over the sheetmaterial previously treated with the dispersed binder 16. Then thedirection of movement of the sheet is changed so that the said layer ison the underside of the moving sheet. Then the back of the sheet istapped, so as to cause falling away of those of the said macroscopicparticles and flakes not directly in contact with the dispersed, wetbinder. The whole is then dried, warmed, rolled, and wound up, asdescribed previously.

Such'equipment used in this example as is not illustrated in the drawinghas already been described in my said Patent 2,603,575.

Products made as described reflect radiant energy, particularly when themetal used is aluminum. They permit passage of air and blowing of smokethrough them. The layer of applied flake metal, although porous, iscontinuous over the crossovers of the strands of the fabric. The flakemetal is especially adherent after application of the mist spray andsubsequent processing and resistant to being brushed from the surfaceduring use.

It will be understood that it is intended to cover all changes andmodifications of the examples of the invention herein chosen for thepurpose of illustration which do not constitute departures from thespirit and scope of the invention.

What I claim is:

1. In making a metallized sheet, the process which comprises applying toa surface of a flexible, fibrous, air permeable sheet an aqueousdispersion of fine, undissolved particles of normally solid,non-volatile, thermoplastic resin binder material in limited proportionto avoid saturation of the sheet and to supply the said particles inspaced relationship to each other, then applying over the spacedparticles of water-wet binder material a layer of heat reflecting metalflakes in uncovered condition, removing those of the applied flakes notadhered to the dispersed binder material, subjecting the sheet materialso treated to an elevated temperature to volatilize the water presentand soften the thermoplastic binder material, pressing the applied metalflakes upon the said sheet and the binder therein in softened condition,and then cooling the whole, the result being a sheet having the bindermaterial adhered to the sheet and metal flakes adhered to the hinder,the flakes having uncovered reflecting faces, and the flakes definingbetween them spaces that are permeable to air.

2. The process of claim 1 in which the metal flakes as applied to thesaid sheet are interspersed with additional fine solid particles ofthermoplastic binder material in dry form and in limited proportion notexceeding parts by weight for of total weight of the mixed binder andmetal flakes so as to preserve air permeability of the finished product.

(References on following page) .Re mu es Ci d in h file of h s p enUNITED STATES PATENTS 8 Schramm Q July 15, 1952 Rand Mar. 10, 1953 RandMar. 10, 1953 FOREIGN PATENTS Great Britain Nov. 13, 19.24

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1. IN MAKING A METALLIZED SHEET, THE PROCESS WHICH COMPRISES APPLYING TOA SURFACE OF A FLEXIBLE, FIBROUS, AIR PERMEABLE SHEET AN AQUEOUSDISPERSION OF FINE, UNDISSOLVED PARTICLES OF NORMALLY SOLID,NON-VOLATILE, THERMOPLASTIC RESIN BINDER MATERIAL IN LIMITED PROPORTIONTO AVOID SATURATION OF THE SHEET AND TO SUPPLY THE SAID PARTICLES INSPACED RELATIONSHIP TO EACH OTHER, THEN APPLYING OVER THE SPACEDPARTICLES OF WATER-WET BINDER MATERIAL A LAYER OF HEAT REFLECTING METALFLAKES IN UNCOVERED CONDITION, REMOVING THOSE OF THE APPLIED FLAKES NOTADHERED TO THE DISPERSED BINDER MATERIAL, SUBJECTING THE SHEET MATERIALSO TREATED TO AN ELEVATED TEMPERATURE TO VOLATILIZE THE WATER PRESENTAND SOFTEN THE THERMOPLASTIC BINDER MATTERIAL, PRESSING THE APPLIEDMETAL FLAKES UPON THE SAID SHEET AND THE BINDER THEREIN IN SOFTENEDCONDITION, AND THEN COOLING THE WHOLE, THE RESULT BEING A SHEET HAVINGTHE BINDER MATERIAL ADHERED TO THE SHEET AND METAL FLAKES ADHERED TO THEBINDER, THE FLAKES HAVING UNCOVERED REFLECTING FACES, AND THE FLAKESDEFINING BETWEEN THEM SPACES THAT ARE PERMEABLE TO AIR.